The present invention relates generally to the field of underground boring and, more particularly, to a system and process for detecting, plotting, locating and removal of organic and inorganic compounds in the subsurface with minimum environmental impacts.
One area of application is cleanup of polluted sites. The advantage of the invention is the detection and removal of contaminants at their source (often referred to as hot spots). A horizontal boring unit is assembled at the site and drilling initiated by directing the head at an inclined angle to the surface. Water or other fluid is injected continuously to remove soil and cuttings and transport to the surface where it is analyzed using a single or combination of volatile organic analyzer, combustion meter, chromatography, infrared and ultra-violet and mass spectroscopy, Geiger counter, wet test methods, pH, ORP, conductivity meters, infrared, X-ray Florescence, and/or Inductive Coupled Plasma. An operator continually analyzes the data and re-directs the boring head toward areas with the highest concentrations of contaminants. Once the location of a hot spot is determined, various methods can be utilized for removal and treatment. For light phase non aqueous liquids (LNAPL) such as gasoline (BETX) or dense phase non aqueous liquids (DNAPL) such as percholoroethylene (PCE) or trichloroethylene (TCE), one method is to insert a Well Evacuator™ in the pipe and aspirate liquid and vapor to the surface for treatment and disposal. To unlock remaining trace residuals, steam or hot air can be injected, followed by application of vacuum in a pulsed or continuous mode of operation.
Upon achieving low or non-detect or concentrations the boring tool is re-directed to remaining hot spots until the site is clean and ready for closure.
Likewise, pockets of polychlorinated biphenyl (PCBs) can be identified and removed from river beds. The Hudson river has large concentrations of PCBs that are the result of diffusion from silts into river water. PCBs are heavier than water and have low mobility and solubility. Removal by conventional dredging technologies is time consuming, expensive and may lead to additional contamination of river water by exposure to contaminated dredge spoils. Clean Mole™ is less invasive than dredging. A single pipe is inserted into the river bed minimizing disturbance of silt. Once a pocket of PCBs in located it is transported to the surface using Well Evacuator™ or other means for treatment and disposal. Remaining trace amounts of PCBs are then treated in-situ using anaerobic or other suitable technologies by injection of suitable microbes and nutrients.
Also, radioactive waste sites can be cleaned up at minimum cost and reduced personnel exposure. McClellan AFB, CA., Savanah River, N.C., Rocky Flats, Colo., and Richland Wash. are examples of sites where radioactive contaminants have been detected. Site investigation and treatment is very expensive using existing technologies. Clean Mole™ allows detection and treatment in-situ minimizing exposure and costs. Once the hot spot is detected, cement or other solidification/agents are injected rendering the radioactive contaminants immobile and reducing radioactivity to acceptable levels.
A second application is mining of minerals especially, precious minerals found in veins. Current practices are open pit mining and tunnel mining. These methods result in environmental damage in the form of abandoned mines that leach pollutants into our potable water resources. Using the Clean Mole™ technology minimizes tailings and destruction and reduces the costs of metals recovery. The boring tool is directed along the vein continually analyzing and transporting cuttings to the surface for treatment without creating large open pits that later become environmental problem areas. As an alternate, the tip of the boring tool is redirected to the surface and a larger auger or pipe is inserted in the formation allowing higher volumes of ore to be mixed with water and the slurry pumped or conveyed to the surface.
A third application is mapping of the sub-surface. Cuttings can be analyzed to determine both their chemical and physical nature. This information can be used to supplement existing well log boring data. Geologic Information Systems (GIS) can be constructed readily from this data to provide a accurate display of the subsurface. This data is valuable for placement of wells, pipes, conduits and cables at minimum costs.
The general technique of boring a horizontal underground hole, analyzing the cuttings real time, and using this information to locate and remove concentrated contaminants is a cost effective approach that saves time and money. Remediation is directed to the areas with highest concentrations of contaminants. In accordance with such a horizontal boring technique, also known as micro tunneling, horizontal directional drilling (HDD) or trench-less underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an inclined angle with respect to the ground surface. A drilling fluid is typically flowed through the drill string, over the boring tool, and back up the bore hole in order to remove cuttings and dirt. The cuttings and drilling fluid are analyzed at the surface and the information evaluated through the use of operator knowledge to sophisticated computer models. Based on this information, an operator controls the direction of the boring tool head continually seeking areas of highest concentration of contaminants. Once a pocket of contaminants is located it is removed from the subsurface either directly by the boring tool or by conventional technologies such as excavation, pumping soils vapor extraction, and treated or destroyed. The entire process is completed in weeks to months rather than years or decades.
It can be appreciated that present methods of detecting and treating underground contamination is cumbersome, fraught with inaccuracies, and expensive. Moreover, the inherent delay resulting from sampling and analysis coupled with imprecise placement of wells in dilute contaminant streams adds costs and health risk during cleanup of sites. By way of example, the MEW site in Santa Clara County has spent tens of millions of dollars over 20 years in an attempt to clean up chlorinated solvents in ground water. The source is leaking underground storage tanks (LUST) that were used by manufacturers of semi conductors over thirty years ago. Although a considerable amount of money has been expended final cleanup and closure have not been attained and no accurate timeline has been established.
During conventional remedial investigation of contaminated sites vertical wells are punched or bored and a casing is placed to allow sampling of groundwater and/or soil vapor. Placement of the wells is often based on proximity to the original source such as an underground tank. If analysis exceed drinking water standards, additional sampling is conducted followed by installation of additional wells to define the extent of contamination. Health and ecological risk are evaluated and a remedial investigation report is prepared. Often additional wells are installed to monitor spread of contamination. Once the extent of contamination is established, feasibility studies are conducted to determine and select treatment options
There exists a need in the excavation industry for an apparatus and methodology for analyzing, interpreting and controlling an underground boring tool to map the subsurface and provide an economical and environmentally friendly means for treatment of contamination and recovery of valuable minerals than is currently attainable given the present state of the technology. There exists a further need for such an apparatus and methodology that may be employed in vertical and horizontal drilling applications. The present invention fulfills these and other needs.